Silver and platinum jewellery

Precious metals are those which do not displace hydrogen from acids i.e. they are below hydrogen in electrochemical series. They belong to heavy metals.

Precious metals include silver, gold and platinum and other metals of platinum family i.e. palladium, rhodium, ruthenium, osmium and iridium. Precious metals show high resistance to corrosion and aggressive chemical environments. They do not oxidize and are resistant to so-called aqua regia (a 3:1 mixture of concentrated hydrochloric acid and concentrated nitric acid). They have high density, good plasticity and high melting point, except for silver and gold. Precious metal alloys are those where average content of precious metals is higher than 10%.

Platinum alloys containing gold, silver, palladium, iridium, copper and other metals are used for production of thermocouples and windings of heating furnaces. A 950 assay platinum and copper alloy is used in jewellery.

Pure silver is used in electronics in the form of tapes and wires and for galvanizing of other metals. Industrial silver is used for soldering of alloys with thermal expansion similar to that of glass with molybdenum and palladium for the production of vacuum components. Alloys of silver with copper, gold and platinum are used for coinage, manufacturing of accessories and cutlery in jeweller’s trade. Silver in the form of AgBr and AgCl is used in photochemistry for films and light-sensitive paper.